The present invention relates to a boring tool used to form a bore when a plug, an anchor or the like used to mount an instrument is inserted into a brittle wall substrate such as a plaster board.
Heretofore, as such a boring tool, a drill is used which is to be mounted on an electric drill and has a shank portion having a helical shape except its mounting portion, and a cutting edge having a pointed tip.
Also, as one for a manual driver, JP utility model publication 6-32325 proposes such a boring tool.
But when various kinds of instruments are mounted to a brittle wall surface substrate such as a plasterboard, troublesome work was needed. Namely, after boring has been made in the wall surface substrate with a drill mounted to an electric power tool, the drill is removed from the power tool and a driver bit or a hexagonal socket has to be mounted on the power tool to thread a screw or a bolt into a plug or anchor inserted through an instrument into the wall surface substrate. Otherwise, it was necessary to prepare another power tool to which is mounted a driver bit or a hexagonal socket in addition to a power tool to which is mounted a drill.
Also, in order to solve this problem, JP utility model publication 6-32325 for a manual driver was proposed. But since the driver bit is fitted in the boring tool only at its tip, rattling will develop, thus making accurate boring difficult. Also, if it is used with an electric power tool, there was a problem that the fitting portion tends to get damaged soon.
According to this invention, there is provided a boring tool comprising a cutting portion at one end thereof, a driver engaging portion at the other end thereof, a shank arranged between the cutting portion and the driver engaging portion, the driver engaging portion being formed with a hexagonal hole and a cross recess at bottom of the hexagonal hole for receiving the tip of a cross head driver or driver bit.
According to the present invention, there is also provided a boring tool comprising a cutting portion at one end thereof, a driver engaging portion at the other end thereof, a shank 6 arranged between the cutting portion and the driver engaging portion, the shank being formed with a helical groove for discharging cuttings, the driver engaging portion having a hexagonal outer shape and formed with a hexagonal hole and a recess at bottom of the hexagonal hole for receiving the tip of a driver, a circular flange provided between the driver engaging portion and the shank and having a larger diameter than the outer diameter of the shank, the cutting portion having a pointed tip and a substantially conical shape spreading from the pointed tip toward the outer periphery of the shank, a first recess formed by cutting off substantially a 180xc2x0 section of the cutting portion as seen axially from the pointed tip with an edge in the rotational direction forming a cutting edge, and a second recess formed by cutting off substantially a 90xc2x0 section of the remaining 180xc2x0 section, the second recess being separated from the first recess by a thin-walled partitioning wall.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: